Spirit levels and line levels are employed for different leveling purposes and are accordingly typically packaged and sold as discrete items. Exemplary line levels are illustrated and described in U.S. Pat. No. 3,878,617, U.S. Pat. No. 4,068,386, and U.S. Pat. No. 4,109,392. GB 2210167 illustrates and describes a pocket level having a horizontal bubble vial and a vertical bubble vial, and a detachable line level.
Spirit levels may be provided with angle finders for enabling the determination of the angle of an inclined surface. Exemplary spirit levels with angle finders are illustrated and described in U.S. Pat. No. 359,580, U.S. Pat. No. 935,807, U.S. Pat. No. 1,126,548, U.S. Pat. No. 1,802,131, U.S. Pat. No. 2,506,115, U.S. Pat. No. 2,541,880, U.S. Pat. No. 5,177,873, U.S. Pat. No. 5,531,031, U.S. Pat. No. 6,477,781, AU-A-13950/83, and DE 3413449 A1.